Three-Dimensional Interconnected Reticular Porous Carbon From Corn Starch By a Sample Sol-Gel Method Toward High-Performance Supercapacitors With Aqueous and Ionic Liquid Electrolytes

A three-dimensional interconnected reticular porous carbon (3D-RPC) with a large surface area of 1535 m(2) g(-1) by a sol-gel method followed by carbonation as well as a chemical activation process using corn starch as a carbon precursor was demonstrated. The 3D-RPC shows the ultrahigh specific capacitance of 372 F g(-1) at a current density of 0.5 A g(-1) in a 2 M KOH electrolyte, and the 3D-RPC//3D-RPC symmetry supercapacitors achieved a high energy density of 9.2 Wh kg(-1) as well as long cycle life with the capacitance retention of 90% after 10000 cycles. Furthermore, [BMIm]BF4/AN ionic liquid was selected as the electrolyte to improve the potential operating window where the high specific capacitance of 218 F g(-1) at a current density of 0.5 A g(-1) can be achieved. A 3D-RPC based symmetry supercapacitor in [BMIm]BF4/AN delivers an outstanding energy density of 24.5 Wh kg(-1), which is higher than that of most previously reported carbon materials. Considering the high purity and low cost of corn starch as well as the excellent capacitive performance of the 3D-RPC, the current study provides an effective strategy for the design of low-cost toward high-performance carbon-based supercapacitors.